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Biomedical subjects

Rajeev Agarwal

Publications and source records attributed to Rajeev Agarwal.

6 recordsLinked to original sources
PubMed2006

Sexual dimorphism in immune response genes as a function of puberty.

BACKGROUND: Autoimmune diseases are more prevalent in females than in males, whereas males have higher mortality associated with infectious diseases. To increase our understanding of this sexual dimorphism in the immune system, we sought to identify and characterize inherent differences in immune response programs in the spleens of male and female mice before, during and after puberty. RESULTS: After the onset of puberty, female mice showed a higher expression of adaptive immune response genes, while males had a higher expression of innate immune genes. This result suggested a requirement for sex hormones. Using in vivo and in vitro assays in normal and mutant mouse strains, we found that reverse signaling through FasL was directly influenced by estrogen, with downstream consequences of increased CD8+ T cell-derived B cell help (via cytokines) and enhanced immunoglobulin production. CONCLUSION: These results demonstrate that sexual dimorphism in innate and adaptive immune genes is dependent on puberty. This study also revealed that estrogen influences immunoglobulin levels in post-pubertal female mice via the Fas-FasL pathway.

Animals↗
PubMed2005

Detection of rapid-eye movements in sleep studies.

One of the key features of rapid-eye movement (REM) sleep is the presence of bursts of REMs. Sleep studies routinely use REMs to classify sleep stages. Moreover, REM count or density has been used in studies involving learning and various psychiatric disorders. Most of these studies have been based on the visual identification of REMs, which is generally a very time-consuming task. This and the varying definitions of REMs across scorers have warranted the development of automatic REM detection methodologies. In this paper, we present a new detection scheme that combines many of the intrinsic properties of REMs and requires minimal parameter adjustments. In the proposed method, a single parameter can be used to control the REM detection sensitivity and specificity tradeoff. Manually scored training data are used to develop the method. We assess the performance of the method against manual scoring of individual REM events and present validation results using a separate data set. The ability of the method to discriminate fast horizontal ocular movement in REM sleep from other types of events is highlighted. A key advantage of the presented method is the minimal a priori information requirement. The results of training data (recordings from five subjects) show an overall sensitivity of 78.8% and specificity of 81.6%. The performance on the testing data (recording from five subjects different from the training data) showed overall sensitivity of 67.2% and specificity of 77.5%.

Adolescent↗
PubMed2002

Computer-aided spatial classification of epileptic spikes.

The authors present a method that can be used to identify exemplar spikes from prolonged EEG recordings. To achieve this they have calculated single dipole source models for each automatically detected spike-like waveform. They used a dipole source algorithm that is computationally light and can be run on-line during EEG acquisition. Although a single dipole source model may not provide anatomically accurate information about the location of generators of all epileptiform abnormalities, it does provide a novel spatial parameter that may be useful in its own right. The authors use this spatial parameter and present the relative spatial density of the dipole locations in the form of three planar projections of the spherical model (a view from above, a view from the right, and a view from behind) and allow users to define the x-, y-, and z-coordinates of points of interest within the spherical model. They then present 10 example waveforms of events that have dipole source model locations that occur close to that seed coordinate. Overall, they found that this method performs very well for frequent events, but does not perform well for rare events or for diffuse EEG abnormalities.

Computer-Aided Design↗
PubMed2002

Digital tools in polysomnography.

Recent advances in the computing power and storage devices have made computer-based recording of polysomnograms (PSGs) very attractive. Digital PSGs offer the possibility of automating many tedious and time-consuming tasks of identifying sleep related events. Automation not only alleviates these laborious tasks, but also introduces a measure of objectivity in the scoring of various discrete events. In this paper we briefly review some automatic methods that have been previously developed by the authors. Automatic sleep staging methods is emphasized with some illustrative results on inter-scorer variations. We also discuss the leg movement event, respiratory event, sleep spindle and rapid-eye-movement detection methods.

Computers↗
PubMed2002

Extradural myxopapillary ependymoma with sacral osteolysis--a case report.

Extradural ependymomas arising from filum terminale externa in the sacrococcygeal region are very rare. Since 1937, out of 58 cases reported in English literature, only 13 cases of tumor located presacrally in the retrorectal space, have been reported. The authors report a 38 yrs old male with a primary ependymoma of the sacrococcygeal region causing extensive sacral destruction.

Adult↗